Intrauterine contraceptive device

ABSTRACT

Intrauterine contraceptive device is an integral filamentary body with a substantially sinusoidal flexible stem. At its leading end, the stem terminates in a pair of laterally extending flexible arms and, at its trailing end, terminates in a pair of laterally and axially rearwardly extending relatively inflexible arms, shorter in length than the arms at the leading end. Trailing arms serve to anchor the device relative to the cervix while the leading arms, as well as the stem, are free to conform to changes in position caused by muscular contractions of the uterus.

United States Patent Pharriss et al.

[4s] July 11, 1972 [54] INTRAUTERINE CONTRACEPTIVE DEVICE [72] Inventors: Bruce B. Pharrlss, Cupertino; Max Anlilter, Portola Valley, both of Calif.

[73] Assignee: Aha Corporation [22] Filed: Aug. 5, 1970 [2|] Appl. No.: 61,141

[S 6] References Cited UNITED STATES PATENTS 3,454,004 7/l969 Leiningeretal ..l28/l30 3,250,271 5/1966 Lippes................... ...............l28/l30 Primary Examiner-Richard A. Gaudet Assistant Examiner-G. F. Dunne Attorney-Steven D. Goldby and Paul L. Sabatine [57] ABSTRACT Intrauterine contraceptive device is an integral filamentary body with a substantially sinusoidal flexible stern. At its leading end, the stem terminates in a pair of laterally extending flexible arms and, at its trailing end, terminates in a pair of laterally and ly rearwardly extending relatively exible arms. shorter i ngth than the arms at the leading Trailarms serve to anchor the device relative to the cervix while leading arms, as well as the stem, are free to conform to changes in position caused by muscular contractions of the uterus.

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INVENT Bruce B. Pharri BY Max Anliker IN'I'RAUIERINE CONTRACEPTIVE DEVICE BACKGROUND OF THE INVENTION This invention relates an intrauterine contraceptive device, and more especially, to a device adapted for comfortable retention in the uterus and resistance to expulsion.

Intrauterine contraceptive devices have become an increas ingly more important means of birth control. Widely known devices include the Lippes Loop, Margulies Spiral, Birnberg Bow, and Grafenberg Ring. In general, these devices are integral filamentary bodies formed of thin rods or tubes of polymeric material bent to a shape which will abut against the walls of the uterus.

Low cost, relatively long useful life, and freedom from regular intervening acts by the user are significant theoretical advantages of an intrauterine contraceptive device, as contrasted with other techniques of birth control. Thus, such devices are fabricated by simple molding procedures from inexpensive polymeric materials. When properly inserted by a physician or paramedical technician, the device should remain in place until removed and provide an efl'ective birth control means during that period. Conscious periodic acts by the user, such as taking a daily pill, are avoided and failures due to patient inadvertence should be slight.

Despite these advantages, intrauterine contraceptive devices have not achieved their full potential in population control or family planning. Even in developing nations, where low cost is vital, these devices have not been unqualified success. This unhappy result is due in large part to the high failure rate or large number of unwanted pregnancies by users. Undoubtedly, the leading cause of such failure is expulsion of the device by large numbers of females. Often this expulsion goes undetected and the female unknowingly has no birth control protection.

Because of the increasing problem of overpopulation and the benefits which would flow from an effective intrauterine device, a vast amount of research has been conducted to improve the retention of these devices. Numerous shapes have been proposed including rings, loops, "1" and "M" shapes. Recently, devices have been described which are provided with arms at either end to resist expulsion. Thus, U. S. Pat. No. 3,467,089 describes an intrauterine device having an elongated straight stem and a pair of elongated arms, of identical length and nature, extending from either end thereof. In the patented device, the two pairs of arms are stiffened with wire springs to provide anchoring means at either end of the device. Because the trailing arms of this device are quite long, there is a substantial dilation of the uterus which stimulates uterine muscular contractions. Because of its shape, the patented device cannot give with these forces but reacts against them. Another related intrauterine device is described in U. S. Pat. No. 3,454,004. That device has an elongated straight stem connecting an elongated leading end strand having an outwardly bowed curvature and a trailing end strand having an inwardly bowed curvature. This device too has a shape which prevents it from fully adapting to muscular contractions of the uterus without being expelled therefrom.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of this invention to provide an intrauterine contraceptive device of improved configuration which will resist expulsions resulting from muscular contractions of the uterus.

Another object of this invention is to provide an intrauterine device which can adapt itself to the shape of the uterine lumen during muscular contractions of the uterus and, in doing so, assume a configuration which makes it more difficult to be expelled.

ln accomplishing these objects, one feature of this invention resides in an intrauterine contraceptive device comprising an integral filamentary body having a flexible substantially sinusoidal stem. At its leading end, the stem terminates in a pair of laterally extending flexible arms and terminates at its trailing end in a pair of laterally and axially rearwardly extending relatively inflexible arms which are shorter in length than the arms at the leading end.

Other objects, features and advantages of this invention will be apparent to those skilled in the art from the detailed description of the invention which follows and from the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG 1 is a frontal view of the improved intrauterine contraceptive device of the invention;

FIG. la is a side view of the intrauterine contraceptive device of the invention;

FIG. 2 is a schematic representation, partially in cross-section, of the device of the invention in place in a relaxed uterus; and

FIG. 3 is a schematic representation, partially in cross-section, of the device of the invention in place in the uterus and temporarily distorted by muscular contractions of the uterus.

DETAILED DESCRIPTION OF THE INVENTION As illustrated in FIGS. 1 and la, the intrauterine contraceptive device 10 of the invention has a flexible substantially sinusoidal stem 11. By substantially sinusoidal" in reference to stem 11 is meant that the stem has an undulating waveform appearance. Stem l1 terminates at its leading end in a pair of laterally extending flexible arms 12 and 13. At its trailing end, stem 11 terminates in a pair of laterally and axially rearwardly extending relatively inflexible arms 14 and 15.

Preferably and as illustrated in FIG. 1, stem 11 is comprised of three curved sections 16, 17, and 18. Although the curved sections can decrease in size toward the trailing end of device 10, typically they are equal in size. Thus, sections 16 and 17 advantageously are curves tangent an imaginary line b--b which is parallel to the longitudinal axis a-a of stem 11 and the area circumscribed by axis a-a and each of sections 16, 17, and I8 is equivalent.

Leading arms 12 and 13 extend laterally from stem 11 and advantageously these arms extend axially forwardly of stem 11. Thus, arms 12 and 13 preferably subtend an angle of 120 to 180 with respect to each other which angle is bisected into equal parts by axis a-a. Arms 12 and 13 are of the same length and are substantially longer than trailing arms 14 and 15. Typically, each of arms 12 and 13 is from 40 to percent of the axial length of stem 11; that is, of the length of axis a--a. These arms are of uniform rounded or elliptical cross-section and have rounded or blunt end portions. Arms 12 and 13 act to provide a physiologically acceptable surface to receive the force of muscular contractions of the uterus. Their primary function is not to anchor or secure the intrauterine device in the uterine lumen but rather to yieldingly receive the forces and transmit such forces to stem 11.

Trailing arms 14 and 15 are smaller in size and less flexible than leading arms 12 and 13. Typically, each of trailing arms 14 and I5 is from 10 to 40 percent of the axial length of stem 11. They extend both laterally and axially rearwardly and preferably subtend an angle of from to with respect to each other, which angle is bisected into two equal parts by axis a-a. Trailing arms 14 and 15 can be of uniformed rounded cross-section but preferably are tapered toward their extremities, as illustrated in FIG. 1. These arms serve to provide a fixed trailing anchor point for the intrauterine device within the uterus.

In use and as illustrated in FIG. 2, device 10 is disposed within lumen 19 of a uterus schematically represented as being defined by side-walls 20, top wall 21, and cervix 22. Device 10 is disposed within lumen 19 with leading arms 12 and 13 abutting against uterine top wall 21 and the ends of trailing arms 14 and 15 abutting against and anchoring the device toward the lower portion of uterine side-walls 20. Crests of curved stem sections 16, I7, and 18 also abut against side-walls 20 of the uterus.

During muscular contractions of the uterus, device is not expelled, but rather, temporarily distorts in shape in response to the forces applied. Important to the invention is that trailing arms 14 and abut against and partially embed within uterine sidewalls providing a fixed anchoring point for the device. Thus, as a generally downward uterine muscular contraction begins at the upper uterine wall 21, leading arms 12 and 13 are forced downwardly, compressing and shortening the axial length of sinusoidal stem 11. As stem 11 shortens, it also widens, that is, crests of curved sections l6, l7, 18 are forced outwardly. As force from a sidewall 20 is applied to curved sections l6, 17, and/or 18, stern ll will tend to elongate and trailing arms 14 and 15 will be secured against the lower portion of sidewalls 20. Because the trailing arms provide a fixed anchoring point, the device will not be expelled. FIG. 3 illustrates device 10 in a temporarily compressed or stressed configuration during a contraction of the uterus. When the uterus relaxes, device 10 resumes its original unflexed configuration, illustrated in FIG. 2.

Thus, the intrauterine contraceptive device of this invention is specially designed to adapt itself to the various forces which can be applied by uterine muscular contractions and to assume a stressed shape that resists expulsion. Individual elements of the device act in concert to ensure that the device will remain in the uterus until intentionally removed. Leading arms of the device provide a receiving surface for forces of uterine contractions but do not restrict downward mobility of the device. Sinusoidal stern can shorten axially and spread outwardly in response to axial forces transmitted form the leading arms; the crests of its curved sections serve to return the device to its unilexed condition when forces are applied thereto. Trailing arms provide a fixed anchor point for the device and prevent expulsion through the cervix. Because the trailing arms are relatively short, they do not substantially dilate the uterus which can result in unwanted stimulation of muscular contractions.

Devices of the invention are provided in different sizes to accommodate various size uterine lumens. One typical device is of the shape illustrated in FIG. I and has leading arms each 2 cm. in length, an axial stern length of 3 cm., a fully extended stern length of 6 cm., trailing arms each 0.7 cm. in length, and is formed of filamentary polymeric material having a diameter of 0.2 cm. However, these dimensions are not critical and the individual elements can be smaller or larger depending on the needs of the particular patient. in this specification and the appended claims, all dimensions, relative dimensions and angles are set forth for the device in an unflexed condition.

One can insert the device of the invention into the uterine lumen through the cervix in the conventional manner. leading arms can be disposed forwardly, trailing arms disposed rearwardly and the device loaded into a conventional cylindrical inserter whose upper end is entered into the cervix. Upon discharge of the device into the uterine lumen by force of a plunger, the device assumes the configuration illustrated in FIG. 2. By grasping and disposing rearwardly the trailing arms, the device can be withdrawn from the uterus in a simple manner.

Various biologically acceptable flexible, resilient, polymeric materials can be used to form the intrauterine device of the invention. Illustrative materials include polyethylene, ethylenevinyl acetate copolymers, silicone rubbers, ethylene-ethyl acrylate copolymers, polybutylmethacrylate, plasticized nylon, and plasticized polyvinyl chloride. With these materials, the device can be readily fabricated by conventional mold ing techniques. Because trailing arms 14 and 15 are shorter in length than leading arms 12 and 13, the trailing arms are inherently less flexible, even when formed of the same material. However, numerous means, well known in themselves, can be used to further stiffen trailing arms 14 and 15, when desired. In one embodiment of the invention, arms [4 and 15 can be stiffened with wires embedded in and constituting their axial cores and totally encased in the biologically acceptable polymeric coating. in another embodiment, the polymeric material in arms 14 and 15 can be cross-linked to a greater degree than that in the remainder of the device, thereby rendering arms 14 and is relatively non-resilient in respect to the remainder of the device. This can be accomplished, for example, by cross-linlting arms 14 and 15 using electromagnetic radiation or heat, while suitably shielding the remainder of the device from these cross-linked initiators. Alternatively, arms 14 and 15 can be formed from a different and stilfer material than the stern and leading arms 12 and 13 and then adhesively secured to the trailing end of stem 11. By "relatively inflexible" used to describe trailing arms 14 and 15 is meant that these arms are less flexible than leading arms 12 and i3 and stem 1 l.

Intrauterine contraceptive device of the invention is of unique shape to adapt itself to the shape and muscular contractions of the uterus without being expelled. In addition, the device is of sufficient surface area to provide contraceptive efficacy. Besides being used as a mechanical intrauterine contraceptive device, the device of this invention can be employed as a drug container to release antifertility agents or other drugs to the uterus. When this is desired, the device will incorporate the antifertility agent or other drug within it interior and be formed of a suitable polymeric membrane to release the antifertility agent or drug to the uterus at a predetermined therapeutically effective level. One suitable means of construction for such a drug releasing intrauterine device is disclosed in copending application Ser. No. 42,786, filed June 2, 1970 for an invention of A. Zaffaroni, assigned to the assignee of this invention. The disclosure of that copending application is relied upon and incorporated herein by reference.

While the invention has been described and illustrated with reference to certain preferred embodiments thereof, those skilled in the art will appreciate that various modifications, changes, omissions and substitutions can be made without departing from the spirit of the invention. It is intended, therefore, that the invention be limited only by the scope of the following claims.

What is claimed is:

I. An intrauterine contraceptive device, non-irritating to the uterus, adapted for comfortable retention therein and resistant to expulsion therefrom, and which does not cause erosion or perforation of the uterine walls, said device being comprised of an integral filamentary body having a flexible substantially sinusoidal stem, said stem terminating at one end in a pair of opposed laterally extending flexible leading arms adapted to abut against the fundus of the uterus and which define a physiologically acceptable surface to receive the force of muscular contractions of the said uterus, and terminating at its other end in a pair of opposed laterally and axially rearwardly extending relatively inflexible trailing arms which are shorter in length than the said leading arms, said trailing arms adapted to provide a fixed anchor point for the intrauterine device within the uterus, said sinusoidal stem between said leading and trailing arms having a lateral extent of least equal to that of said trailing arms; and whereby, when inserted in the uterus, said device can adapt itself to the shape of the uterine lumen during muscular contractions of the said uterus without being expelled therefrom.

2. The intrauterine device of claim 1 wherein the said leading arms subtend an angle of 120 to l with respect to each other and the said trailing arms subtend an angle of to with respect to each other.

3. The intrauterine device of Claim 1 wherein the said trailing arms are tapered toward their extremities.

4. The intrauterine device of claim 1 wherein each of the leading arms has a length of 40 to 80 percent the axial length of the stem and each of the trailing arms has a length of 10 to 40 percent the axial length of the stem.

5. The intrauterine device of claim 1 wherein the leading arms each are about 2 cm. in length, the trailing arms each are about 0.7 cm. in length, and the longitudinal axial stem length is about 3 cm.

6. The intrauterine device of claim 1 wherein the stem is comprised of three curved sections.

6 7. The intrauterine device of claim 6 wherein the area cirto 180 with respect to each other and each of the leading cumacribed by the longitudinal axis of the stem and each of arms having a length of 40 to 80 percent the axial length said curved sections of the stem is equivalent. of the stem, and

8. The intrauterine contraceptive device of claim 1 comprissaid stem terminating at its other end in a pair of relatively i 5 inflexible trailing arms extending laterally and axially a flexible substantially sinusoidal stem formed of three rearwardly and wbwndins an a of to ith curved secfimm respect to each other and each of the trailing arms having said stem terminating at one end in a pair of flexible leading a length of 10 to 40 P the mm] "m of the stemarms extending laterally and subtending an angle of 120 10 

1. An intrauterine contraceptive device, non-irritating to the uterus, adapted for comfortable retention therein and resistant to expulsion therefrom, and which does not cause erosion or perforation of the uterine walls, said device being comprised of an integral filamentary body having a flexible substantially sinusoidal stem, said stem terminating at one end in a pair of opposed laterally extending flexible leading arms adapted to abut against the fundus of the uterus and which define a physiologically acceptable surface to receive the force of muscular contractions of the said uterus, and terminating at its other end in a pair of opposed laterally and axially rearwardly extending relatively inflexible trailing arms which are shorter in length than the said leading arms, said trailing arms adapted to provide a fixed anchor point for the intrauterine device within the uterus, said sinusoidal stem between said leading and trailing arms having a lateral extent of least equal to that of said trailing arms; and whereby, when inserted in the uterus, said device can adapt itself to the shape of the uterine lumen during muscular contractions of the said uterus without being expelled therefrom.
 2. The intrauterine device of claim 1 wherein the said leading arms subtend an angle of 120* to 180* with respect to each other and the said trailing arms subtend an angle of 90* to 180* with respect to each other.
 3. The intrauterine device of claim 1 wherein the said trailing arms are tapered toward their extremities.
 4. The intrauterine device of claim 1 wherein each of the leading arms has a length of 40 to 80 percent the axial length of the stem and each of the trailing arms has a length of 10 to 40 percent the axial length of the stem.
 5. The intrauterine device of claim 1 wherein the leading arms each are about 2 cm. in length, the trailing arms each are about 0.7 cm. in length, and the longitudinal axial stem length is about 3 cm.
 6. The intrauterine device of claim 1 wherein the stem is comprised of three curved sections.
 7. The intrauterine device of claim 6 wherein the area circumscribed by the longitudinal axis of the stem and each of said curved sections of the stem is equivalent.
 8. The intrauterine contraceptive device of claim 1 comprising a flexible substantially sinusoidal stem formed of three curved sections, said stem terminating at one end in a pair of flexible leading arms extending laterally and subtending an angle of 120* to 180* with respect to each other and each of the leading arms having a length of 40 to 80 percent the axial length of the stem, and said stem terminating at its other end in a pair of relatively inflexible trailing arms extending laterally and axially rearwardly and subtending an angle of 90* to 180* with respect to each other and each of the trailing arms having a length of 10 to 40 percent the axial length of the stem. 